If you own a boat, it is your responsibility to keep your passengers safe. That means NOT tethering a child, but following the USCG guidelines and having a life jacket on board for each person. And when it is a child, you should be responsible enough to make them wear it.

I have cruised some 15,000 NM and have yet to have seen a cruising child tied to their boat - in fact, many of the children are just like the adults in teather and PFD use.

Now having said that, our son lived aboard and cruised with us full time from when he was 2 until 6 - then we spent part time cruising on the boat until he was 10. He wore a PFD whenever he was in the tender (regardless of weather). He wore a PFD on deck when he went forward while under way in any weather or when we were docking or anchoring (when it might be likely that we are well occupied and not notice him taking a swim). We also had a harness for him, just like us - it went unused because in any kind of rough weather it made no sense for him to even come into the cockpit.

Now, having said that, this was on an Ingrid 38, with high toe rails, stanchions the length of the boat and netting from amidships aft (with weather clothes the last 9 feet).

Now the rest of the story - did he ever fall over? All our friends were worried about that and our land lubber family members varied from appauled to just concerned about our child and the life we were leading. Yes, he did fall over, just once. When he was two, while at a dock getting a hard dodger fitted, he went to the gangway opening and went to close the pelican hook (like he had done before) and fell over between the boat and the dock.

It scared him and we nearly died. We had heard later that other cruisers had similar things happen - and they often happened only once, ever.

Keep them in a PFD until they can swim well, then put them in a PFD whenever they are in a situation where they could fall in - on the boat or the dock. Once our son learned how to swim like a fish and was able to jump around over the main boom like a monkey, we relaxed a bit.

Use common sense
Oh, and I have another story about my dog leashed on deck (as was required by the marina I was in, in S.F)... and he went over while I was in the shower, ashore....